1. Field of the Invention
The present invention relates to an automotive air conditioner and, more particularly, to an automotive air conditioner having a cooling power control device for effectively controlling a cooling power of a cooling device which is fed by a car-carried electric power source.
2. Description of the Prior Art
In the field of the automotive air conditioner, a method of automatically controlling the cooling power of a cooling device fed by a car-carried power source in order to attain energy-saving has been disclosed in Japanese Patent Application Kokai (Laid-Open) No. 120536/76 in which, by means of a switch mechanically interlocked with a position of a temperature regulating member, such as air mixing damper, a cooling device, e.g. a known compressor in cooling operation, is intermittently disconnected from the car-carried electric power source by an electromagnetic clutch.
However, since the prior art cooling power control device is controlled by the temperature regulating member, it is not possible to accurately determine an actual thermal condition in an automotive passenger compartment (hereinafter referred to as passenger compartment). The temperature regulating member will be affected by a number of factors, including a change in the heat exchanging power of a heat exchanger located in an air duct, a change of the rotational speed of the compressor due to variations in the rotational speed of the engine, a temperature change of the cooling water of the engine which acts as a heat source, or a change in the temperature of air outside the passenger compartment. Such changes often give rise to a hunting phenomenon in the driving and stopping operations of the compressor. To avoid such hunting, the conditions for decision must be made less severe, and therefore it has been difficult to attain precise energy efficiency.